The following description of the background of the invention is provided simply as an aid in understanding the invention and is not admitted to describe or constitute prior art to the invention.
Tamoxifen is a standard of treatment for hormone receptor positive breast cancer patients after primary treatment. Five to ten years of tamoxifen therapy reduces the risk of recurrence and death in these patients. Yet, many patients do not complete their full course of therapy, frequently due to unpleasant side effects of the drug.
Tamoxifen is a pro-drug which is converted to the highly active Endoxifen for full effectiveness. Conversion of Tamoxifen to Endoxifen is through a metabolic pathway dependent on genetic variation, such as that in CYP2D6 (2D6). Although 2D6 genotyping has been promoted to predict response to Tamoxifen and toxicity, the direct association on an individual level is controversial.
An effective method of predicting response to Tamoxifen is needed.